Following up on https://reviews.llvm.org/D62221, this change introduces
the setting plugin.process.gdb-remote.try-to-use-g-packet. When that is on
and the server supports the use of 'g' packets, those will be used regardless
of whether 'p' packets are supported.
Using 'g' packets can improve performance by reducing the number of packets
exchanged between client and server when a large number of registers
needs to be fetched.